Seems like you know how you can improve. If you don't see any plays that won't open the board up try just swapping tiles, maybe you'll force her to open the board for you. Losing a turn is worth it if playing is going to set her up for a double or triple word tile.
If she has a much larger vocabulary than you then you might be boned. Scrabble really relies on knowing a ton of bullshit "Scrabble words" too, if your wife knows these and you don't you have no chance. Words like qi, qat, xi, joe, and za are essential for playing those high-score tiles when the rest of your hand sucks. If you take advantage of bonus tiles and S's you can score a ton of points with just a few tiles.
But if you're more or less equal in terms of the kinds of words you're using you just need to be more patient. Like kubev said, every time you lose ask yourself what you could have done differently and make a conscious effort to follow through on the next game. Getting pissed off even though you know exactly what mistake you're making isn't going to help anything.
Also keep in mind that luck does play a huge component in the game, you can only tell who is truly better by playing a ton of games and seeing who wins more often. In any given game it's easy for one player to win by getting the blanks and more high-scoring letters even if they're not thinking as strategically.
this is why i only play rummikub
I like the idea of that game but seeing the name spelled out raises my blood pressure. It's a family favorite and without fail every game will have multiple instances of people taking 10+ minute long turns that culminate in a board with multiple illegal strings and the question "Wait, which tiles came from my hand again?"
I haven't played in a few years.
